The invention relates to a method for determining a steering rack force for a steering system of a vehicle, in which a first steering rack force is ascertained as a function of at least one force that occurs in the steering system or at least one torque that occurs in the steering system. The invention further relates to an open-loop and/or closed-loop control device for a steering system for a vehicle which is adapted to carry out such a method.
A target steering torque is ascertained in modern steering systems, for example electric power steering (EPS) or steer-by-wire (SbW) steering systems. A steering torque on a steering means of the steering system, for example on a steering wheel, is set to the target steering torque so as to support the force that is applied by the driver when steering the vehicle, or to counteract the force that is applied by the driver. It is known to ascertain the target steering torque as a function of the steering rack force.
A method for determining a force that acts on a steering gear is known from DE 10 2009 002 706 A1. According to this method, a force that acts on the steering gear is ascertained based on the motor torque. This method provides the driver of the vehicle with good feedback on the real force conditions in the steering gear. However, strong feedback is perceived to be disturbing at least in some instances.
It is the object of the invention to provide a method for determining a steering rack force which provides less strong feedback on the force conditions in the steering system for reasons of driving comfort, in particular when such feedback is currently not required.